There have been debates regarding the issue on whether working memory could guide attentional selection. Some researchers have reported that working memory contents guided attention automatically (Soto et al., 2005). On the other hand, Woodman and Luck (in press) reported that they found no evidence of attentional capture by working memory. The current study tried to find an integrative explanation for the conflicting results. In our experiments, while memorizing a single color, participants had to do a visual search task. Each search item had different colors. In one condition, one of search items had the same color as the memory prime (memory matching distractor). In the other condition, there was no memory matching distractor. Although the participants knew that the memory matching item would never be a target, the presence of the memory matching distractor slowed the visual search, reflecting memory-driven attentional capture. However, when perceptual processing of search stimuli was more demanding by increased target-distractor similarity, or the onset of the search was delayed long enough for cognitive control to be implemented, the effect of memory-driven attentional capture was eliminated. From these results, we suggested perceptual difficulty and the time course of cognitive control as explanations to resolve the conflict between the previous studies. We also suggested that the memory matching item was prioritized involuntarily in the visual search because a target template could be stored in visual working memory with other contents to be memorized. However, cognitive control could dissociate the target template from search-irrelevant working memory contents, modulating the effect of attentional capture by working memory.

This research was supported by a grant (M103KV010017-06K2201-01710) from Brain Research Center of the 21st Century Frontier Research Program funded by the Ministry of Science and Technology, the Republic of Korea.